Malaysia Airlines: How the world is searching for MH370

The Chinese patrol vessel Haixun 01 which has detected 'pulses' from the sea
is just one of a huge international effort searching for the plane

A Royal Australian Air Force E-7A Wedgetail takes off from Perth Airport on route to conduct search operations for missing Malaysia Airlines Flight MH370 in southern Indian Ocean, near the coast of Western Australia,Photo: ROB GRIFFITH/AP

By Jonathan Pearlman, Sydney

7:44PM BST 05 Apr 2014

It was the moment that the crew of the Haixun 01, a 430ft Chinese patrol and survey ship had long been hoping for.

A signal from the deep was picked up on Friday by highly sensitive monitoring equipment on board the 5,000-ton vessel.

At first the signal was vague. But on Saturday a stronger pulse of signals was received, raising hopes that the black box recorder of Malaysia Airlines MH370 may finally have been found.

The Haixun 01 patrol and survey ship (REUTERS)

The possible discovery comes amid one of the largest searches in aviation history, which has deployed an international team of more than 1,000 people, dozens of aircrafts and ships and the scouring of hundreds of thousands of square miles of ocean.

It is a scattergun approach that has relied heavily on luck, but was seen as the only possible prospect of success in a hunt described by an Australian official as worse than finding a needle in a haystack because “we’re still trying to define where the haystack is”.

In recent days, authorities decided to expand the search in a desperate last-ditch effort to find the aircraft’s black box before its locator pinger falls silent, possibly as soon as Monday.

A British submarine and a British ship with underwater locator capabilities rushed to the search area late last week, joining a United States pinger detector towed by an Australian ship and a Chinese rescue vessel which also had a black box detector.

The towed pinger locator (TPL-25) sits on the deck of the Australian Defence Vessel Ocean Shield (REUTERS)

Meanwhile, the air and sea search was expanded Saturday to include 10 military planes, three civilian jets and 11 ships – its largest contingent yet.

The ships responsible for the underwater searches, Britain’s HMS Echo, a hydrographic survey ship, the Haixun 01, and Australia’s Ocean Shield, entered the area on Friday and were assigned to cover tracks along the sea about 150 miles long. The Ocean Shield is towing an underwater microphone, the TPL-25, which can detect pings, as well as the Bluefin-21, an autonomous underwater vehicle which can comb the ocean floor for signs of wreckage.

The ships have been scouring an area more than 1,000 miles from Perth, believed to be the most likely point at which the Boeing 777 ended its mysterious flight.

The specially-designed US underwater locator is towed beneath the water to try to detect pings at a depth of up to 20,000ft. The pinger, which transmits a signal every second, has a 30-day battery life, though experts say it could continue to transmit a weakened signal for a further five days to two weeks.

Ships with locators can travel only at about three knots during searches at depths beneath 10,000ft, leaving them with little chance of finding the black box in a search area which, on any given day, can span an area the size of Ireland. The zone’s waters typically have depths of about 8,000ft to 16,000ft but ridges on the ocean floor or even marine life can sometimes interfere with the pulses from the pinger.

Phoenix International personnel sit with the towed pinger locator on the deck of the Australian Defence Vessel Ocean Shield (REUTERS)

In the early days of the search, the primary technique was overflights by planes, whose paths are carefully plotted each day by authorities co-ordinating the search in Australia. Gradually, ships, reached the area, allowing them to retrieve suspected debris which was spotted by the planes. Finally, the search began its underwater phase after the locators and submarine reached the zone.

The black box, which captures flight data and records cockpit communication, can withstand extreme heat, pressure and water and its data can last for years. The difficulty is finding it once the pinger ends: it took two years to find the black box from an Air France 447 flight which crashed in 2009, even thought debris was found from the plane within 24 hours.

As William Marks, a US navy commander, observed, finding the black box without evidence of debris is “just a guess”.

“The best thing we can do right now is put these assets in the best location based on the best guess we have, and kind of let them go,” he said.

The team of surveillance planes and ships from nations including China, Australia, Malaysia, the US, Japan, Britain, New Zealand and Korea has scoured hundreds of thousands of square miles of ocean but failed to spot any wreckage which might point to the location of the plane.

The difficulty for planes is that it takes about four hours to fly to the search zone, so flyovers are limited to about three hours before fuel loads require them to return to an air force base near Perth. Each plane is assigned a search zone of about 10,000 square miles and typically flies up and down designated tracks about 140 miles long. The tracks are spaced about 17 miles apart because the planes are able to scope an area about 8.5 miles on each side.

On a search on Friday which the Telegraph joined, an Australian air force P-3 Orion spotted a “small, white and square-ish” object, though it was yet to be identified.

“I couldn’t tell what it was – a white sort of shape in the water,” said Nicholas Barr, a flying officer in charge of navigation and communications. “I was confident enough to investigate an object. Hopefully they can go back and find something.”

A team of experts including British and US aviation investigation board members and analysts from Boeing, Rolls Royce and Inmarsat, the British satellite firm, has been poring over the few known details about MH370’s flight path to try to find a more precise location for the plane’s crash point. The search area was dramatically shifted north to a new zone more than a week ago – and it has been moving slowly northward in the days since.

This followed analysis of the last known sighting of the plane by a Malaysian military radar, whose data — following closer examination — suggested the plane was flying faster than thought and would have run out of fuel somewhere west, or even north, of Perth.